Semiconductor processing chambers, such as the 300 mm Novellus Altus chambers, accumulate tungsten dust in the pedestal wells as the chamber operates. Large amounts of this residual dust build up loosely on the bottom side of the pedestals. Currently, removal of this dust is accomplished by spraying compressed dry air (CDA) into the pedestal well, which produces a plume of tungsten dust that permeates throughout the interior and exterior of the chamber. Operators utilize a vacuum hose to capture as much of the tungsten dust as possible as the dust escapes from the chamber well. However, this cleaning method produces a cloud of tungsten dust in an uncontrolled and unpredictable manner. Attempts to slowly spray small amounts of CDA into the well simultaneously with utilizing the vacuum hose to gather the dust as it escapes from the other side of the pedestal have been unsuccessful at controlling the tungsten dust plumes.
Recent studies have indicated that creating the tungsten dust cloud is creates a safety concern and health concern. According to “Explosion Temperatures of Metals and Other Elemental Dust Clouds” by Kenneth L, Cashdollar and Isaac A. Zlochower, the contents of which are hereby incorporated by reference, a tungsten dust cloud consisting of small particles (1-3 μm) has the potential to explode if exposed to an ignition source. Because of the nature of the processing chambers, such as the Altus, the potential for explosion exists. In addition, exposure to contact with the tungsten dust cloud can cause acute health effects such as irritation to the eyes and skin. Irritation to the eyes can include watering and redness. Irritation to the skin can cause skin inflammation such as reddening, scaling, and itching. Inhalation of portions of the tungsten dust cloud can cause irritation to the lungs and mucus membranes.